The advent of new laws concerning the disposal of hazardous waste materials may impose problems for the safe disposal of high energy density lithium cells employing a sulfur-containing component. Lithium-sulfur dioxide (Li/SO.sub.2) and lithium thionyl-chloride (Li/SOC12) cells are now being manufactured with safety devices such as fuses, vents, diodes, etc. which allow them to be safely used under various conditions. The advantages of lithium-thionyl chloride cells are their high energy density, flat discharge characteristics, excellent shelf life and operability over a wide temperature range. To promote wide use of these types of cells, it is necessary that they can be safely disposed of whether they are fully discharged, partially discharged or fresh cells. In addition to a sulfur-containing component in the cells, other components such as cyanide may be present from the use of cyanide-containing electrolyte solutions.
Various chemical means have been employed by the battery industry to dispose of toxic or hazardous waste products. Simple neutralization methods have been employed in the lead-acid battery industry. For example U.S. Pat. No. 4,652,381 discloses a battery plant waste water treatment process in which a process of treating industrial waste water contaminated with environmentally unacceptable amounts of sulfuric acid and heavy metals such as lead, copper or zinc is disclosed which permits lowering of the concentration of the contaminants to a level permitting discharge to the sewer. Waste water resulting from floor wash and spray washing of lead acid batteries prior to shipment from the manufacturing facility contains sufficient sulfuric acid to cause the pH to normally be at a level of about 2 along with heavy metal contaminants present in concentrations which require treatment for removal before the discharge water will meet EPA standards. The water to be treated is directed to a first reaction and settling vessel where calcium carbonate is added along with an oxidation medium such as air which also functions to stir the stored waste water. Sufficient calcium carbonate is added to bring the pH of the solution to a level of about 5 and at the same time react with the heavy metals present such as lead, copper or zinc. Calcium sulfate and respective heavy metal carbonates precipitate and settle to the bottom of the treatment zone where they may be readily removed. In a second treatment vessel, calcium hydroxide, along with enough calcium carbonate to maintain an excess of carbonate ion, is added to complete separation of the heavy metals. Final removal of precipitate from the solution is accomplished through a suitable filter.
Reactive liquids have been used to safely dispose of residues of active metals such as sodium, potassium and lithium. For example, U.S. Pat. No. 3,459,493 discloses a process that provides a controlled method for the conversion of the active metal to the corresponding metallic compound (e.g., hydroxide, chloride) by contacting said metal with a two-layer liquid system, the top layer being a low specific gravity nonreactive liquid and the bottom layer being a high specific gravity reactive liquid. The presence of the nonreactive liquid phase limits the reaction rate between the metal and the reactive liquid, and provides a heat sink for the heat of reaction. Depending upon the objects to be achieved, the various process parameters may be altered in such a way as to insure that the reaction is always kept under control and that no dangerous buildup of byproduct hydrogen occurs. These parameters include: ratio of reactive liquid to nonreactive liquid, system temperature, choice of liquid phases, and salts present. Simple two-layer liquid systems consisting of an inert hydrocarbon oil as the top layer and water as the bottom layer are generally preferred, but in some cases it may be desirable to add other reactants, stabilizers, or antifoam agents to produce other desired results.
Chemical scrubber units have been employed to contain and neutralize corrosive fluids such as SOCl.sub.2 and SO.sub.2. For example, U.S. Pat. No. 4,303,745 describes a chemical scrubber 327.0? for containing and neutralizing toxic, corrosive thionyl chloride and sulfur dioxide acid fluids vented by a primary electrochemical cell. The scrubber unit includes an inlet tube coupled to the electrochemical cell by which thionyl chloride and sulfur dioxide vented by the cell are conveyed to an elongated, generally rectangular distribution trap disposed within a housing of the scrubber unit. The distribution trap contains sodium carbonate or sodium bi-carbonate for reacting chemically with and neutralizing thionyl chloride vented by the cell and received within the trap and is itself surrounded within the housing by soda lime for chemically reacting with and neutralizing both sulfur dioxide and thionyl chloride vented by the cell and received within the trap. The distribution trap distributes and disseminates thionyl chloride and sulfur dioxide received thereby over a substantial volume for increasing the exposure of the thionyl chloride and sulfur dioxide to the neutralizing materials (sodium carbonate or sodium bi-carbonate and soda lime) thereby increasing the material utilization of the neutralizing materials.
U.S. Pat. No. 4,448,859 describes a method for deactivating a thionyl chloride cell by introducing a solution of aluminum chloride in thionyl chloride into a discharged cell and allowing the solution to react with the negative active material in the cell.
U.S. Pat. No. 4,637,928 discloses a method for neutralizing reactive material of articles such as batteries. Specifically, a method and apparatus are disclosed for treating batteries in a manner permitting safe disposal thereof, each of the articles comprising a casing having reactive material therein, wherein the article casing is opened to allow access to the interior thereof, fluid is introduced to the interior of the opened casing, and any evolved gas is removed. The steps of opening the casing, introducing fluid and removing gas are performed simultaneously in a reaction vessel which is supplied with the fluid and which is in communication with gas collecting and scrubbing means. The reaction vessel preferably comprises a deluged hammermill and a tank. The hammermill is supplied with articles by a remotely fed conveyor and which discharges into a tank, fluid is supplied to the hammermill and to the tank, and the gas collecting and scrubbing means is in communication with both the hammermill and tank. The fluid preferably is water or an alkaline neutralizing solution. The gas scrubbing means can include a first stage for removing acid gases and a second stage serving as a demister. Liquid is withdrawn from the tank, filtered to remove solids and then returned. A portion of the returned liquid is supplied to the hammermill and another portion is passed through a heat exchanger for cooling and then returned to the tank.
It is an object of the present invention to provide a method for treating high energy density sulfur-containing cells to render the cells safe for disposal.
It is another object of the present invention to provide an improved chemical disposal method for lithium cells containing a sulfur-containing component to render the cells safe for disposal.
It is another object of the present invention to provide an improved chemical disposal method for Li/SOCl.sub.2 and Li/SO.sub.2 cells to render the cells safe for disposal.
It is another object of the present invention to provide a chemical disposal method for sulfur-containing cells also containing toxic components such as cyanide to render the cells safe for disposal.
Other objects and advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed disclosure and the appended claims.